Conical Light Concentrator for Optical Code Readers
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Solution Overview
Problem
Existing optical code readers face challenges in maximizing light collection from optical codes while minimizing ambient light interference, particularly in miniaturized designs where increasing the size of the receiving section reduces reading speed and efficiency.
Innovation Solution
An optical receiving device with a solid body of transparent material, featuring a light input face, a perpendicular output face for the photodetector, and an oblique face that utilizes total internal reflection to concentrate light efficiently, allowing for a small photodetector device and high reading speed, along with a cylindrical or Fresnel lens for optimized light collection and reduced ambient light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance between the photodetector device and the input opening of the receiving optics is increased to reduce the field of view and minimize ambient light noise, then the noise is reduced, but the size of the receiving section increases
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional conical receiving optics structure. The conical shape with its sloping reflective surface allows light to be concentrated along the optical axis while maintaining a compact footprint, effectively utilizing the third dimension to achieve noise reduction without increasing overall device volume.
Solution Approach 2:
The patent changes the geometric parameters of the receiving optics by introducing a conical structure with a specific opening angle (2θ). This parameter optimization allows the system to achieve the desired field of view restriction and noise reduction while maintaining a compact size, as the conical geometry naturally limits the acceptance angle of ambient light.
2Illumination intensity
If the light collection area (input opening) is increased to collect a stronger optical signal, then the signal intensity is improved, but the size of the receiving section increases
Solution Approach 1:
The conical structure utilizes three-dimensional space to concentrate light from a relatively small input opening onto the photodetector. The sloping reflective surfaces redirect light rays at various angles toward the optical axis, effectively concentrating the optical signal without requiring a large collection area, thus maintaining compact dimensions.
Solution Approach 2:
The patent combines the light collection function and the light concentration function into a single integrated conical structure. The reflective inner surface serves both to collect incoming light and to concentrate it onto the photodetector, eliminating the need for separate components and reducing overall device size while maintaining signal intensity.
3Illumination intensity
If the sensitive surface area of the photodetector device is increased to collect more light, then the optical signal is improved, but the pass band of the electronic receiving circuit is reduced
Solution Approach 1:
The conical receiving optics acts as an intermediary that concentrates light from the optical code onto a small photodetector surface. This intermediary structure amplifies the optical signal through geometric concentration, allowing a small photodetector to receive sufficient light intensity for high-speed reading without sacrificing bandwidth.
Solution Approach 2:
The patent optimizes the parameters of the conical structure, particularly the opening angle 2θ and the ratio between input opening diameter and photodetector diameter, to achieve maximum light concentration. This parameter optimization ensures that even a small photodetector receives adequate optical signal for high-speed operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient light concentration with a small photodetector area, enhancing the signal-to-noise ratio and allowing for high-speed reading capabilities in a compact form factor, while simplifying manufacturing and reducing bulk.
Implementation Method 1
an oblique face with respect to both said input face and said output face, characterized in that the mutual orientation of the faces of the optical receiving device is such that the light entering from said input face within a desired field of view is concentrated onto said output face by total internal reflection
Data Source
AI summary
An optical receiving device (31) for an optical code reader is described, comprising a solid body, of a transparent material, having a light input face (32), a light output face (33) for coupling with a photodetector device (30), said output face (33) being substantially perpendicular to said input face (32), and an oblique face (34) with respect to both said input face (32) and said output face (34), characterized in that the mutual orientation of the faces (32-38, 40-42, 40′, 41′, 42′) of the optical receiving device (31) is such that the light entering from said input face (32) within a desired field of view is concentrated onto said output face (33) by total internal reflection.